This disclosure relates generally to position location and, more particularly, to positioning with signals from regional satellite systems.
Global navigation satellite systems (GNSS) provide positioning data to users throughout the world. Using information from different GNSS satellites, it is possible to determine location within a global coverage area and to synchronize with satellite time.
More recently, regional satellite systems have been developed to augment existing GNSS systems. Regional satellite systems serve specific parts of the world and, among other things, aim to improve the accuracy, integrity, and availability of global satellite positioning within their respective service areas.
Mobile devices are increasingly available which can receive and process signals from both global and regional satellite systems. By their very nature, these devices change position and can therefore move into and out of the coverage areas of different regional satellite systems.
As a result, a mobile device may search for a regional satellite vehicle that is not accessible from its current location. This fruitless search wastes time, power, and search capacity and thus degrades positioning performance. Alternatively, the mobile device may be programmed to wait until after a position fix is obtained before determining the availability of regional satellites. This also lengthens the time needed to arrive at a fully accurate position and results in reduced performance.